Microsoft provides the following high-level shot of the app's panoramic UI, but if you're familiar with Facebook on Windows Phone, you'll notice the differences immediately.

Combining Microsoft's notes with my observations, since I use this app almost every day, we see the following changes:

Beautiful new panorama UI. And not only is it redesigned, but it more closely mimics the layout and navigational theme of the Facebook web site. So instead of Most Recent as the default pane, we now see News Feed. Next up is Notifications (which used to be to the left for some reason), then Photos, which takes on a nicer, grid-based layout. And then the Profile pane, which represents "you." Here, you'll see favorite links like Profile, Friends, Messages, Nearby, Groups, Pages, Photos, and Notes.

Visible App bar. The default News Feed screen sports an always-visible App bar with Check In, Add, and Take Photo buttons (plus Refresh, Filter, Settings, Change Banner Image, and Logout menu options under the "More" ellipsis). These buttons bring your most-wanted options right up front and, again, correspond to recent changes in the Facebook web UI. For example, to check in with Facebook 2.2 and earlier, you had to navigate to your Profile pane and tap "Places" and then Check In. Dumb.

Likewise, the new "Add" functionality works like Facebook on the web now with the ability to filter a post to only those friends you wish. And the new Take Photo offers a quick shortcut to what is one of Facebook's most frequently-used features, a nice addition.

Banner image. Facebook recently added the notion of a "cover" image for your profile's timeline view, and this is the header image people will see when they look you up on the service. The new banner image functionality in the Facebook 2.3 app curiously doesn't utilize this image, but instead provides a matrix of images from your saved photos, but the effect is similar and attractive. (It's also optional if you don't want it.)

Friends, Messages, and Notifications icons. At the top of the banner area in the app, you'll see three icons that are identical to the three icons in the Facebook web header: Friends, Messages, and Notifications. (You can see this in the shot above.) And they work the same in the app as they do on the site, as expected, again providing consistency and a nice way to access much-used functionality. These icons aren't tied to a particular pane, so they stay there as you navigate around.

Better performance. The Facebook app has always been a bit slow, especially when you do things like check-in or scroll through the news feed. This seems to have improved in version 2.3.